Preparation Of The Composites Of Corn Straw Cellulose And Gold,Silver And Their Alloy,and Their Antibacterial Applications

The production of corn stalks in the northeast region is huge,at present,its treatment methods are mainly based on incineration.Incineration of corn stalks will cause serious atmospheric pollution problems.Therefre,the development of green,efficient and environmentally friendly corn stalks has important scientific value and environmental protection significance.Corn stalk contains a large amount of cellulose components,its extraction and modification are expected to develop into high value-added application materials.Recent studies have found that gold and silver nanomaterials have excellent stability,biocompatibility and excellent antibacterial activity.The development of gold and silver composite materials based on corn straw cellulose is expected to develop new antibacterial active materials with a wide range of green,environmental protection and application.In this paper,corn stalks were used as raw materials,and nanocellulose was firstly extracted and prepared,then the hydrothermal synthesis method of silver,gold and gold-silver alloy nanocomposites based on corn stover cellulose was further studied,the material was explored in terms of bacteriostatic properties.In this experiment,the corn-stalk cellulose-silver,gold and gold-silver alloy nanocomposites were prepared by hydrothermal synthesis method,in which corn stalk nanocellulose was used as reducing agent and stabilizer.The obtained straw nanocellulose microcrystalline cellulose-silver,gold and gold and silver alloy nanocomposites was characterized by ultraviolet-visible spectroscopy(UV-Vis),Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),atomic force microscopy(AFM)and X-ray diffraction(XRD).1.Preparation and antibacterial activity of corn stalk cellulose-silver nanocomposites.The results of TEM and AFM showed that the synthesized nanocellulose-silver nanoparticles were spherical and evenly distributed on the nanocellulose filaments.XRD measurements show that the silver nanoparticles in the composite have a crystal structure.The antibacterial activity of corn stover cellulose-silver nanocomposites against Gram-positive bacteria,Gram-negative bacteria and fungi was tested.The bacteriostatic results showed that corn stalk nanocellulose-silver nanocomposites have strong bactericidal effects on bacteria and fungi.2.Preparation and antibacterial activity of corn stalk cellulose-gold nanocomposites.It was observed by atomic force microscopy(AFM)that the cellulose was network-like and interlaced with a width of 15-20 nm,a length of several hundred nanometers,and a height of 80-100 nm.Nanoparticles are attached to the cellulose filaments in the composite.Ultraviolet-visible absorption spectroscopy(UV-Vis)showed characteristic absorption peaks at 525 nm,529 nm,and 545 nm,indicating the presence of gold nanoparticles in the composite.The microstructure of the composite was further observed using a transmission electron microscope(TEM),the results showed that most of the spherical gold nanoparticles were attached to the nanocellulose filaments.The size of the gold nanoparticles on the corn stalk nanocellulose is related to the initial amount of chloroauric acid added in the synthesis.In this study,composites with average gold nanoparticles of 22 nm,32 nm and 40 nm were prepared.The results of XRD showed that the gold nanoparticles in the composites had a crystal structure.Fourier transform infrared spectroscopy(FTIR)was used to determine the change of functional groups in the process of extracting and synthesizing composites.The bacteriostatic test on the prepared straw cellulose-gold nanocomposite showed that the material had strong inhibitory effect on bacteria and fungi,with the increase of the ratio of gold/cellulose unit from 0.086:1 to 0.34:1,the inhibitory activities of Escherichia coli,Candida albicans and Staphylococcus aureus are gradually enhanced.3.Preparation and antibacterial activity of corn stalk cellulose-gold silver alloy nanocomposites.The results of atomic force microscopy showed that the cellulose was in a network structure and interlaced with each other,the nanoparticles adhered to the network filaments.The UV absorption spectrum of straw cellulose-gold-silver alloy nanocomposites showed a strong absorption peak in the region of 538-549 nm,which proved that gold-silver alloy nanoparticles existed in the composite.Transmission electron microscopy showed that the morphology of the gold and silver nanoparticles in the prepared composite was spherical.The antibacterial test of the prepared composites showed that the composite had higher antibacterial efficiency against Escherichia coli,Staphylococcus aureus and Candida albicans.The XRD measurement confirmed that the gold and silver nanoparticles in the composite had a crystal structure.The bacteriostatic effect is gradually enhanced as the proportion of Au-Ag used for the initial synthesis increases.